Distichopora robusta sp. nov., the first shallow-water stylasterid (Gnidaria: Hydrozoa: Stylasteridae) fi:-om the tropical
eastern Pacific
Alberto Lindner*, Stephen D. Cairns ^ and Hector M. Guzman
*Department of Biology, Duke University, Box 90338, Durliam, NC, 27708, USA. E-mail: [email protected]
^Department of Zoology, NMNH, Smithsonian Institution, PO Box 37012, W-329, MRC-0163, Washington, DC, 20013-7012, USA.
E-mail: [email protected]. Smithsonian Tropical Research Institute, Box 2072, Balboa, Panama.
E-mail: [email protected]. •'Corresponding author.
Distichopora robusta, the first shallow-water stylasterid coral from the tropical eastern Pacific, is described from the west coast of Panama. The new species is distinguished from all species oí Distichopora described thus far by having robust branches and poorly defined pore rows.
INTRODUCTION MATERIALS AND METHODS
Stylasterid corals comprise about 250 species, making them the second largest group of calcified cnidarians, only the Scleractinia having more species (i.e. 1500;
Cairns, 1999; Cairns et al., 1999). They are distributed worldwide in both deep and shallow-water marine environments, but most species occur in water depths of 200-500m (Cairns, 1984, 1992). Among the tropical shallow-water species, currently assigned to either Stylaster or Distichopora, most form branching, fan-like colonies 5 to 25 cm tall and are remarkable for their bright colours, including violet, red, yellow and orange. These shallow-water species are abundant mostly in the Indo-West Pacific, with only two species•Stylaster blatteus (Boschma, 1961) and Stylaster rosaceus (Green) 1886)•occurring in the eastern Atlantic and a single species•Stylaster roseas (Pallas,
1766)•found in the western Atlantic.
The first descriptions of shallow-water stylasterids were those of the western Atlantic Stylaster roseas and the Indo- Pacific Distichopora violácea (Pallas, 1766). Subsequently, about a dozen additional shallow-water species of Distichopora were described for the Indo-West Pacific. This number was greatly reduced by Boschma (1959), who recognized only four valid shallow, Indo-Pacific species of Distichopora (plus two doubtful species). The most wide- spread of these is D. violácea, ranging from the Red Sea, Seychelles, East Africa, through the Indian Ocean to the central Pacific. Thus far, only for the eastern Pacific have tropical shallow-water stylasterid corals not been described.
Here, we describe Distichopora robusta sp. nov., the first tropical shallow-water stylasterid coral from the eastern Pacific. Collected ofT the coast of Panama, this new species has robust branches and lacks well-developed pore rows, the latter feature traditionally considered as the most important diagnostic characteristic oí Distichopora (Cairns, 1983).
Colonies of Distichopora robusta sp. nov. were collected at depths of 5 to 25 m on the south side of Isla Jicarita, Gulf of Chiriqui, western coast of Panama. Colonies were preserved in 95% ethanol or kept dried, and were studied using methodology as described by Cairns (1983). The abbreviations used are: MZUSP (Museu de Zoología da Universidade de Sao Paulo, Sao Paulo, Brazil); RMNH (Naturalis, Nationaal Natuurhistorisch Museum, Leiden, the Netherlands); USNM (National Museum of Natural History, Smithsonian Institution, Washington, DC, USA).
SYSTEMATICS Class HYDROZOA
Order FILIFERA Superfamily HYDRACTINOIDEA Family STYLASTERIDAE Gray, 1847
Genus Distichopora Lamarck, 1816 Distichopora robusta sp. nov.
(Figures 1 & 2) Type material
Holotype: female colony, 14 cm wide, dried, and scan- ning electron microscope (SEM) stubs 1066-1067 (south side of Isla Jicarita, Gulf of Chiriqui, Panama; water depth: ~12m) [USNM 1020570]. Collected by Hector M. Guzman, 29 August 2002.
Paratypes: male colony, dried (south side of Isla Jicarita, Gulf of Chiriqui, Panama; water depth: 5-25 m) [RMNH Coel. 32150]. Collected by Carlos A. Guevara, 7 February 2003. Female colony, dried (south side of Isla Jicarita, Gulf of Chiriqui, Panama; water depth: 5-25 m) [MZUSP 467]. Collected by Carlos A. Guevara, 7 February 2003.
Additional paratypes: 3 male and 3 female colonies, dried, SEM stubs 1068-1070, and 33 fragments in ethanol (south side of Isla Jicarita, Gulf of Chiriqui, Panama;
944 A. Lindner et al. New shallow-water Pacific stylasterid
Figure 1. Distichopora robusta sp. nov.: (A) holotype colony, 14 cm wide, lateral view; (B) holotype colony, upper view; (C) para- type colony (USNM 1020571), 10cm wide, lateral view.
water depth: 5-25 m) [USNM 1020571]. Collected by Carlos A. Guevara, 7 February 2003.
Etymolog))
The specific name robusta refers to the thick, robust branches of the species.
Diagnosis
Distichopora robusta is distinguished from its congeners by the combination of two characters: (1) having thick, robust branches (up to 2 cm wide) with blunt to slightly clávate tips; and (2) having poorly defined pore rows.
Description
Corallum bushy, attached through a broad encrusting base from which 3-5 contiguous, large-diameter (up to 2 cm) branches originate, each main branch bifurcating repeatedly, terminating in blunt to slightly clávate branch tips 4•5 mm in diameter. Largest colony (holo- type) 4 cm in basal diameter, 10 cm in height, and 14 cm in width, producing a roughly spherical colony of closely
spaced branches (Figure 1). Branches circular to slightly elliptical in cross-section, but not flattened, as in most species of Distichopora. Branch anastomosis rare. All branches somewhat knobby, each knob a small prominence with a short pore row consisting of several gastropores flanked by dactylopore spines (Figure 2E).
Coenosteum reticulate-granular in texture, the coenosteal strips 75•110/im in width and flanked by slits 40-50/im in width, the slits often reduced to elongate pores. Strips covered by tall (up to 28 ¡xm) slender spines, not rounded granules (Figure 2H,I). Coenosteum a dark purple to lavender in colour, the branch tips and central branch core white, and the branch knobs a more intense lavender (Figure 1).
Pore rows poorly defined (Figure 2), short rows of gastropores rarely more than 15 /(m in length occur randomly over the branch surfaces; isolated gastropores surrounded by 4-6 dactylopore spines, and short rows of two or three gastropores also quite common. Small clus- ters of gastropores also occur. Pore rows about 0.8 mm wide. Gastropores flush, circular, 0.17-0.22 mm in
Figure 2. {Opposite) Distichopora robusta sp. nov.: (A) branch cross section showing branch core, ampullae (upper and lower parts) and gastropore tubes with gastrostyles (right); (B) branch cross section showing a pair of U-shaped holes created by Polydora sp. and a long gastropore with gastrostyle and several tabulae (upper part); (C) stereo pair showing short pore row and surface of two female ampullae (notice efferent pore on right upper part of upper ampulla); (D) short pore row; (E) pore row forming a knob; (F) pore row flanked by female ampullae; (G) detail of short pore row; (H) reticulate-granular coenosteal texture; (I) reticulate- granular coenosteal texture; (J) dactylopore spine and adjacent gastropore; (K) stereo pair showing two gastrostyles, with tabulae and elements of diffuse ring palisade (near tip of styles); (L) gastrostyle, tabula (bottom) and rounded elements of diffuse ring
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946 A. Lindner et al. New shallow-water Pacific stylasterid
diameter, and widely spaced, separated from one another by 0.13-0.21 mm. Dactylopore spines typical teardrop shaped, about 0.18 wide and 0.20 mm in length, 0.12 mm in greatest height, and with a dactylotome 0.09 mm in width (Figure 2J). Like the gastropores, the dactylopore spines are also widely spaced. Dactylostyles absent.
Gastropore tubes quite elongate (up to at least 4 mm), oriented perpendicular to branch surface near the exterior, but gently curving 90° to parallel the branch axis, together producing a very porous branch core {^aidaV sensu Cairns, 1991a; Figure 2 A). A very diffuse ring palisade is present in each gastropore at about the level of the gastrostyle tip, consisting of 15•20 small (20•25 /¿m in diameter) rounded elements. Gastrostyles slender (0.08-0.09 mm wide), needle-shaped, but not ridged, covered with rather elongate (up to 30/im), slender spines (Figure 2K-M).
Tip of gastrostyle terminates about 0.4 mm below coenos- teal surface; lower sections of style, below the uppermost tabulae, somewhat smooth, the spines being worn or missing. Height:width of a gastrostyle as high as 50. Deli- cate, elongate gastrostyles held in place by multiple hori- zontal tabulae. Tabulae about 10 ßra in thickness and occur every 0.20-0.45 mm along gastrostyle, some elongate styles having over ten tabulae.
Female ampullae 0.75-0.92 mm in diameter and usually fairly low in relief, having a circular efferent pore 0.20-0.25 mm in diameter directed upward (Figure 2C).
The outer edges of the female ampullae bear radially arranged coenosteal strips. Male ampullae smaller (0.35- 0.45 mm in diameter), often clustered, but also quite low in relief One or two small (50 /¿m), stellate efferent pores occur on the top of each ampullae, the stellate shape caused by small spines projecting into an otherwise circular pore.
The base of most colonies are bored by a lithophagid bivalve. Additionally, many of the branches of most colonies contain a pair of circular, closely-placed, parallel, excavated holes, each about 1.3 mm in diameter that run along the centre of the branch core (Figure 2B) and occasionally come to the surface of the coenosteum. Each of these U-shaped cavities contains a polychaete of the genus Polydora, perhaps P. alloporis Light, 1970, a species known to infest the shallow-water eastern Pacific stylas- terid Stylaster californicus (Verrill, 1866).
DISCUSSION
The 'distichoporine' pore rows oí Distichopora (i.e. a row of gastropores flanked by one or two rows of dactylopores), is diagnostic of the genus; however, the short and poorly- defined pore rows of Distichopora robusta distinguish it from 22 of the other 23 recent species known in this genus (Cairns et al., 1999). Distichopora providentiae (Hickson &
England, 1909), known only from Providence Island, Indian Ocean, has even less well formed pore rows, but is additionally distinguished from D. robusta by having a yellowish white coenosteum, laterally-flattened branches, and almost flush dactylopore spines. Distichopora robusta also differs from the common shallow-water Indo-Pacific species D. violácea in coenosteal texture, ampuUar structure, colony size and shape, branch shape, lack of coordination of gastro- and dactylopores, and in having
The only other Distichopora from the eastern Pacific is D. laevigranulosa (Cairns, 1986, 1991b) from deep-water (166-806 m) off the Galápagos Islands. This species, however, has laterally-flattened branches and well- developed pore rows on branch edges, characters shared by most species of Distichopora but not Distichopora robusta.
Among the 23 species of stylasterids known from the eastern Pacific (Cairns et al., 1999; this study), D. robusta is the first reported south of the United States and north of the Cocos and Galápagos Islands (the latter localities having only deep-water species; see Cairns, 1986, 1991b).
In addition to the south side of IslaJicarita (type locality), D. robusta was also observed in Bajo Catedral, ~ 3 km north- west of the type locality. Both localities are of difficult access, being exposed to large swells and strong currents, and the species has probably only rarely been observed.
The only record probably referring to D. robusta is that of Maté (2003), who reports that on the south side of Isla Jicarita 'large and thick branching styllasterinid corals are
very common in the basaltic walls below 15 m'.
Although corals and coral reefs from the Pacific coast of Panama have been studied for over three decades (see Maté, 2003), recent studies in the Gulfs of Chiriqui and Panama have resulted in the description of several new shallow-water species, including scleractinians (Budd &
Guzman, 1994; Glynn, 1999; Glynn, Maté & Stemann, 2001), octocorals (Breedy & Guzman, 2003a,b, 2004) and a milleporid (de Weerdt & Glynn, 1991). The descrip- tion of D. robusta, a conspicuous stylasterid coral, and the lack of comprehensive taxonomic studies on more diverse groups of corals in the region (e.g. the scleractinian genus Pocillopora Lamarck, 1816) indicate that additional new species of corals from the tropical eastern Pacific may be uncovered in the future.
We are grateful to Carlos A. Guevara, Alexis Lam and Kevan Mantell for field assistance, and Autoridad Nacional del Ambiente (ANAM) and Autoridad Marítima de Panama (AMP) for authorizing the work in Panama and providing the collection and CITES (Convention on International Trade in Endangered Species) permits. We also thank three anonymous referees for valuable comments and suggestions. Alberto Lindner had financial support from CAPES (Fundaçâo Coordenaçâo de Aperfeiçoamento de Pessoal de Nivel Superior) (Brazil), and major funding was provided by the NSF (US National Science Foundation) PEET (Partnership for Enhancing Expertise in Taxonomy) grant (DEB-9978086) to Stephen D. Cairns and Cliff Cunningham. Partial funding was also provided by Funda- ción AVINA and the Smithsonian Tropical Research Institute.
REFERENCES
Boschma, H., 1959. Revision of the Indo-Pacific species of the genus Distichopora. Bijdragen tot de Dierkunde, 29, 121-171.
Boschma, H., 1961. Campagne de la Calypso: Golfe de Guinée.
Stylasterina. Annales de l'Institut Océanographique, 39, 193-225.
Breedy, O. & Guzman, H.M., 2003a. A new species oíPacifigorgia (Coelenterata: Octocorallia: Gorgoniidae) from Panamá.
Zootaxa, 128, 1-10.
Breedy, O. & Guzman, H.M., 2003b. Octocorals from Costa Rica: the Genus Pacifigorgia (Coelenterata: Octocorallia:
Gorgoniidae). Zfiotaxa, 281, 1-60.
Breedy, O. & Guzman, H.M., 2004. New species of the
Budd, A.F. & Guzman, H.M., 1994. Siderastrea glynni, a new species of scleractinian coral (Cnidaria: Anthozoa) from the eastern Pacific. Proceedings of the Biological Society of Washington, 107, 591-599.
Cairns, S.D., 1983. A generic revision of the Stylasterina (Coelenterata: Hydrozoa). Bulletin of Marine Science, 33, 427-508.
Cairns, S.D., 1984. A generic revision of the Stylasteridae (Coelenterata: Hydrozoa). Part 2. Phylogenetic analysis.
Bulletin of Marine Science, 35, 38-53.
Cairns, S.D., 1986. Stylasteridae (Hydrozoa: Hydroida) of the Galápagos Islands. Smithsonian Contributions to ^ology, 426, 1-42.
Cairns, S.D., 1991a. A generic revision of the Stylasteridae (Coelenterata: Hydrozoa). Part 3. Keys to the genera. Bulletin of Marine Science, 49, 538-545.
Cairns, S.D., 1991b. New records of Stylasteridae (Hydrozoa:
Hydroida) from the Galápagos and Cocos Islands. Proceedings of the Biological Society of Washington, 104, 209-228.
Cairns, S.D., 1992. Worldwide distribution of the Stylasteridae (Cnidaria: Hydrozoa). Scientia Marina, 56, 125-130.
Cairns, S.D., 1999. Species richness of recent Scleractinia. Atoll Research Bulletin, 459, 1-12.
Cairns, S.D., Hoeksema, B.W. c& Van der Land, J., 1999.
Appendix: list of extant stony corals. Atoll Research Bulletin, 459, 13-46.
Glynn, PW, 1999. Pocillopora inflata, a new species of scleractinian coral (Cnidaria, Anthozoa) from the tropical eastern Pacific.
Pacific Science, 53, 168-180.
Glynn, P.W., Maté, J.L. & Stemann, L, 2001. Pavona chiriquiensis, a new species of zooxanthellate scleractinian coral (Cnidaria:
Anthozoa: Agariciidae) from the eastern tropical Pacific.
Bulletin of the Biological Society of Washington, 10, 210-225.
Gray, J.E., 1847. An outline of an arrangement of stony corals.
Annals and Magazine of Natural History, 19, 120-128.
Greeff, R., 1886. Ueber westafrikanische Stylasteriden.
Sitzungsberichte der Gesellschaft zur Beförderung der gesamten Naturwissenschaften zu Marburg, 1, 11-21.
Hickson, S.J. & England, H.M., 1909. Lhe Stylasterina of the Indian Ocean. Transactions of the Linnean Society of London, Series 2,12, 345-354.
Lamarck, J.B.P.A. de M., 1816. Histoire naturelle des animaux sans vertèbres, 2. Paris : Verdière.
Light, W.J., 1970. Polydora alloporis, new species, a commensal spionid (Annelida, Polychaeta) from a hydrocoral off central California. Proceedings of the California Academy of Sciences, 37, 459-472.
Maté, J.L., 2003. Corals and coral reefs of the Pacific coast of Panama. In Latin American coral reefs (ed. J. Cortés), pp. 387- 417. Amsterdam: Elsevier Science B. V
Pallas, P.A., 1766. Elenchuszoophytorum sistensgenerum adumbrationes generaliores et specierum cognitarum succinctas descriptiones cum selectis auctorum synonymis. Hagae: FranciscumVarrentrapp.
Verrill, A.E., 1866. Synopsis of the polyps and corals of the North Pacific Exploring Expedition under Commodore C. Ringgold and Captain John Rodgers, U.S.N., from 1853 to 1856;
collected by Wm. Stimpson, naturalist to the expedition; with descriptions of some additional new species from the west coast of North America. Part 3: Madreporaria. Communications of the Essex Institute, 5, 17-50.
Weerdt, WH. de & Glynn, PW, 1991. A new presumably now extinct species oí Millepora (Hydrozoa) in the eastern Pacific.
Zoologische Mededelingen, 65, 267-276.
Submitted 24 February 2004. Accepted 24 June 2004.
